An attempt for a blind steal that goes off. What part was wrong?

NL Texas Hold'em $10 Buy-in + $1 Entry Fee
Level:5 Blinds(75/150) –

Seat 1 is the button
Total number of players : 8
Seat 6: ( $1320 )
Seat 5: ( $1665 )
Seat 10: ( $290 )
Seat 9: HERO ( $925 )
Seat 2: truth88 ( $780 )
Seat 3: venera1 ( $745 )
Seat 1: DUDE ( $1190 )
Seat 8: gmoneyg2 ( $1085 )
Trny:14502815 Level:5
Blinds(75/150)
** Dealing down cards **
Dealt to HERO [ 5c Kd ]
Seat 5 folds.
Seat 1 folds.
Seat 8 folds.

-- right now I’m hoping to steal a blind. With the 290 in front of me I’m ok with him calling which would likely leave the last 4 to fold allowing us heads up. Neither SB or BB have played many hands so far, it even likely they’re on post fold. If they’re to reraise all in which I see unlikely I’m ok to let it go.
HERO raises [400].
Seat 10 folds.
DUDE calls [400].
Seat 2 folds.
Seat 3 folds.

-- Not really ok with this as I know he would only call with a good hand, likely even one that has me buried.
** Dealing Flop ** [ 3s, 4c, 9d ]

-- After a dead flop like this I don’t expect him to think I’ve hit anything, and with Pocket pairs I would likely to have pushed all in preflop.
HERO checks.
DUDE checks.
** Dealing Turn ** [ 2s ]
Your time bank will become active in less than 20 seconds. If you do not want it to be used, please act now.

-- So even though I’ve picked up a open ended I don’t really like it. There’s a lot of people near getting knocked out at the table so it should get aggressive if I can find the right moment to push with the 525 left I probably have a better chance of doubling up then I do drawing to my open ended here. But then, he’s likely to have hit nothing because I only see him calling 400 in position without pushing me all in with a premium hand. So I push
HERO is all-In [525]
DUDE calls [525].
** Dealing River ** [ 8d ]
HERO shows [ 5c, Kd ] high card king.
DUDE shows [ Kh, As ] high card ace.
DUDE wins 2075 chips from the main pot with high card ace.
HERO finished in eighth place.
HERO has left the table.


What was there error in play there? Preflop, on the flop or the turn by not checking/folding?